The present invention relates to a drying apparatus for use in a photosensitive material processing system. More particularly, the present invention relates to a drying apparatus for use in a photosensitive material processing system which is designed to dry a belt-shaped photosensitive material, e.g., a photographic film, photographic paper, etc., in a drying box as such a photosensitive material passes through it.
In an automatic developing processor, which is one type of photosensitive material processing system, a belt-shaped photosensitive material, e.g., a photographic negative film, photographic paper, etc., is successively dipped in various processing solutions while being transported by transport rollers, thereby effecting various processing, i.e., development, fixing and washing. After such processing, the photosensitive material is dried in a drying apparatus before being discharged to the outside of the processing machine.
The drying apparatus has a drying box designed to dry a photosensitive material as passed through it. The drying box is supplied with circulating drying air.
Hitherto, the temperature control for a heater in the drying apparatus has been effected by a single control system. There has heretofore been substantially no example in which two or more control systems are used for the control of the heater, except for the control of electric power capacity (wattage). There has been no example in which the balance control of the circulating air is attained by the control of the heater.
For example, in a case where the drying apparatus of a small-sized photosensitive material processing system called "mini-lab" is designed to use circulating air, as described above, there is no serious problem as long as the circulating air intake opening and the circulating air passage are provided in well-balanced (e.g., bisymmetrical) relation to the photosensitive material passage. However, if circulating air openings are provided on only one side of the drying apparatus or cannot be arranged in a well-balanced layout, a temperature distribution occurs in the drying apparatus.
The temperature distribution exerts a serious influence on the drying characteristics of the photosensitive material, causing the quality of the processing to be degraded. Particularly, in the case of a parallel processing machine wherein two belt-shaped photosensitive materials are processed while being transported in parallel along respective passages, the drying rate differs between the two photosensitive material passages, and it is difficult to appropriately control the drying conditions for both of them.
Another problem is that if the heater uses a material with which the heater resistance is likely to change with temperature, the rush current becomes large. Thus, it is necessary to design the photosensitive material processing system so that the safety factor for the electric power capacity is large.